Enceladus plumes particle fx
You can use a lot of translucent particles

(But you may prefer a more fuzzy (i.e. volumetric) solution)

The result:



This is my setup: 


a planet (diffuse white sphere), 
an atmosphere (bigger sphere with a "Volume Scatter" material), 
a distant area lamp representing the Sun, 
a monkey shaped probe
a randomly subdivided plane with a white "Translucent Shader" as material




The planet has a Particle System emitting 1000 particles, with a "Child" duplication set to 200 (but higher numbers will give you fuzzier plumes, and longer renders).

The particles are emitted slowly along the Normal (0.100) and have a fair amount of Brownian force (0.360). They are not affected by the scene gravity  (Gravity Field weight = 0). They are rendered as "Object" using the subdivided plane as the Duplication object.

You can play a lot with the settings to make it look right. These are my settings:





This can also be used in animation: the plumes are dynamic -- even if maybe too fast with my settings.



I attach my blend file if you want to have a look at how it works.